To make an entity create and walk for a certain time and then die:
1. Make a character.
2. Right click on him to open properties.
3. Change his name to something simple. (Badguy)
4. "Spawn at start" = no
5. "Spawn after delay" = yes
6. "Spawn life" = time in seconds after spawn when he dies.
7. Save changes
8. Create a trigger zone.
9. Right click on trigger zone to open properties.
10. Change main script to "plrinzoneactivateused.fpi"
11. "If Used" = name exact name of the character (Baguy)
So now when the player walks in the trigger zone the Badguy will spawn and walk for X amount of seconds and then die.
I made my Badguy spawn behind a wall and walk in front of the player and then walk behind another wall and "disappear".
Even though that's not what's literally happening it makes the impression that the Badguy walked through a corridor and disappeared.
Ventures of the worlds around us are only limited by imagination.